Absorbent articles are designed to be worn by humans to absorb bodily fluids, such as urine, menstrual fluid and perspiration, etc. Examples of absorbent articles include sanitary napkins, pantiliners, disposable diapers, incontinence pads, tampons and the like.
In use, the absorbent articles are known to acquire a variety of compounds, for example volatile fatty acids (e.g. isovaleric acid), ammonia, amines (e.g. triethylamine), sulphur containing compounds (e.g. mercaptans, sulphides), alcohols, ketones and aldehydes (e.g. furaldehyde) which release unpleasant odours. These compounds may be present in the bodily fluid or may be produced by fermentation once the bodily fluid is absorbed into the pad. In addition bodily fluids can contain microorganisms that can also generate malodorous by products. Unpleasant odours which emanate from absorbent pads when in use may make the wearer feel self conscious.
Various odour controlling materials have been disclosed. In particular, certain zeolitic materials are becoming known for their odour controlling properties. Zeolitic materials are generally quite safe and have been found to control many odours associated with bodily fluids.
Zeolites as odour controlling materials have been disclosed in the art, as is discussed below.
U.S. Pat. No. 4,304,675 discloses a powdered carpet treatment composition containing a natural or synthetic zeolite, which zeolite is preferably zeolite A. The zeolite is said to have a particle size of 3.5 .mu.m and in which about 4% of the particles have a micrometer size of greater than 10 micrometers.
U.S. Pat. No. 4,525,410 discloses a fibre article having antibacterial properties comprising zeolitic particles retaining therein at least one metal ion having bactericidal property and a mixed fibre assembly. The zeolite has a low framework ratio of SiO.sub.2 /Al.sub.2 O.sub.3. The zeolite has the ions Ag.sup.+, Cu.sup.2+ or Zn.sup.2+ associated therewith.
WO 81/01643 discloses the removal of ammonia (and other toxic or potentially toxic nitrogenous irritants) from diapers by incorporating into the diaper an inorganic aluminosilicate zeolite ammonium ion exchange material. The zeolite is said to be synthetic or natural and the only zeolite exemplified is naturally occurring clinophlolite.
U.S. Pat. No. 4,826,497 discloses fibrous absorbent articles intended for the absorption of bodily fluids comprising synthetic zeolites prepared using an organic templating agent prepared in siliceous form in which at least about 90% of the framework tetrahedral units are SiO.sub.2 tetrahedra, which has pore diameters of at least 5.5 .ANG. and has a capacity for absorbed water of not greater than 10% under standard conditions. The framework ratio of SiO.sub.2 /Al.sub.2 O.sub.3 of the synthetic zeolite is high. The Examples all utilize steam treated zeolite Y or silicalite.
WO 91/11977 discloses a method for decreasing odours associated with bodily fluids comprising contacting said fluids with an odour controlling amount of an intermediate framework SiO.sub.2 /AlO.sub.2 zeolite.
In the prior art disclosures all the zeolite odour controlling materials tend to be in the form of very small dusty particles which are difficult to handle on a commercial scale; they generally have a size of &lt;5 .mu.m. Such materials tend to be blown or vacuumed up from absorbent structures moving at high speeds (500-600 items/minute) used on modern catamenial or diaper manufacturing lines and this is a problem.
A system has been suggested to overcome this problem and in particular WO 91/12030 discloses combining particulate carbon odour controlling agents with white coloured zeolite or other "masking materials", using binder materials. This system is however expensive and the effectiveness of the odour control material can be reduced.
The object of the present invention is thus to provide an absorbent article providing odour control using an material which can be handled easily in production of an absorbent article, which has good odour controlling properties and is not expensive.